def f(n):
    d=2
    while d*d<=n:
        if n%d==0:
            return False 
        d+=1
    return True


d=['zero','one','two','three','four','five','six','seven','eight','nine']
a=input().split()
if len(a)!=3 or a[0] not in d or a[1] not in d or a[0] not in d:
    print('Wrong input')
else:
    n = int (str(d.index(a[0])) + str(d.index(a[1])) + str(d.index(a[2])))
    for i in range (1, 1000):
        if f(n - i):
            print(n - i)
            break
        if f(n + i):
            print(n + i)
            break
  
    